FERODO FRICTION RETARDER Caterpillar

Ferodo Friction Retarder

Usage:

Remove Retarder

The following procedure describes the removal of the Retarder unit. Early retarder installations used a 4 bolt mounting, the latest uses a 6 bolt mounting to retain the unit.

NOTE: 1. During disassembly/assembly of the retarder, the greatest care must be taken to keep the exposed parts free of dirt. Thoroughly clean down the outside of the unit before any items are removed.

2. The centre shaft oil seals and the operating cylinder can be changed with the retarder unit in position. Further disassembly will require the unit to be removed from the machine.

1. Park the machine on level ground, apply the parking brake and stop the engine.

2. Remove the magnetic drain plug (1) at the base of the retarder and allow the oil to drain away. The system capacity is approximately 20 litres.

3. Remove the input (2) and output (3) drive shafts.

4. Remove the front (4) and rear (5) adaptor plates fixed to the retarder unit coupling flanges.

5. Remove the oil inlet (6) and outlet (7) hose connections.

6. Remove the breather vent hose (8) connection and the operating cylinder air line connectors (12 and 13), marking the air lines to ensure correct reassembly. Disconnect the electrical connections (14), again marking them to ensure correct reassembly.

7. Support the retarder unit. Unscrew the mounting bolts (9) and remove the retarder from the machine. The complete unit weighs 78 kg. (175 lbs).

Install Retarder

1. Position the retarder unit between its mountings and secure using the mounting bolts (9). Tighten the bolts to a torque of 41 Nm (30 lbs.ft.).

2. Connect the electrical connections (14).

3. Connect the two air lines (12 and 13) to the operating cylinder.

4. Connect the breather vent line (8).

5. Before connecting the oil outlet and inlet hoses, remove the filter assembly (10) element and replace with a new element.

NOTE: On earlier units fitted with bronze filter elements, the element can be cleaned using solvent and then re-fitted. If the filter contains a large amount of sediment it is recommended that the whole oil system is flushed clean.

6. Connect the inlet (6) and outlet (7) hoses and fill the unit with the correct retarder oil up to the filler/level hole. (A dipstick is fitted to earlier units). Replace the filler plug (11).

7. Install the front (4) and rear (5) adaptor plates to the coupling flanges.

8. Install the input (2) and output (3) drive shafts.

9. Remove the drive axle half shafts.

10. Fill the retarder circuit with oil. Refer to the Operation and Maintenance Guide for the particular machine.

11. Start the engine and operate at 1000 rpm. Operate the retarder for several short applications to prime the bellows and circulate the oil. Stop the engine and top up the retarder oil level if necessary.

12. Install the drive axle half shafts.

13. Test and adjust the retarder as detailed in Service Manual HENR 8081 Ferodo Friction Retarder.

Disassemble Retarder

The following procedures and illustrations refer to the later Retarder. The earlier unit (4 bolt mounting) has minor detail differences which do not affect disassembly/assembly procedures.

1. Unscrew the four screws (1) fixing the oil outlet body to the main casing.

2. Remove the oil outlet body. Note the 'O' ring (2) set into the base. Discard the gasket (3).

3. Unscrew the four screws (4) fixing the operating cylinder assembly.

4. Withdraw the operating cylinder assembly complete with the small spring (5) and piston (6) which locates in the end of the internal control valve. Retain the spacer (7) and make note of the number of gaskets used.

5. Remove the front and rear coupling flange locknuts. Discard the locknuts.

6. Remove the front and rear coupling flanges.

7. Remove the rear spacer (8) from the centre shaft.

8. Remove the plug and the outer brass nut (9) from the pressure testing point. Retain the plug and nut. Discard the washer.

9. Remove the 16 locknuts (10) retaining the end cover. Remove the end cover, taking care not to strain the pressure testing point connecting pipe.

NOTE: Take care when separating the end cover from the main casing. The outermost rotor plate (11) may be held to the end cover stator plate (12) by a thin film of oil which may break and allow the rotor plate to fall out during the separation procedure.

10. Withdraw the remaining rotor and stator plates.

11. Withdraw the front spacing collar (13) from the centre shaft.

12. Slide the hub (14) off the centre shaft.

13. Bend back the tab washers locking the pump body retaining bolts (15) and remove both bolts. Discard the old tab washers.

14. Progressively unscrew the three stator pins (16) making sure that the whole of the retarder internal assembly is withdrawn at the same time.

15. Remove the internal assembly complete from the main casing.

Inspect/Replace Worn Parts

1. Inspect the stator plates screwed to the bellows and end cover. If these are damaged or show signs of excessive heat (blueing) they will need replacing. Check the tightness of the stator plate securing screws. The screws should be tightened to a torque setting of 11-14 Nm (8-10 lb.ft.).

2. Inspect the rotor plates (1) and stator plates (2), they should be replaced if they show signs of excessive wear or heat damage.

3. Check the condition of the centre shaft (3), lipseals (4) and coupling flange sealing surfaces (5). If these are at all suspect they should be replaced.

NOTE: Retarder units with the 4 bolt fitting can have 2U0717 sleeves fitted to the sealing circumferrence of the coupling flanges if any wear in this area is evident. Instructions for fitting this item are included with the parts.

Assemble Retarder

New Parts Required

1. Guide the complete internal assembly into the main casing, taking care when guiding the centre shaft through the lipseal in the bottom of the main casing.

NOTE: Apply a coating of Locktite 648 to the threaded bores of the stator pin locating holes before reassembly.

2. Progressively tighten the three stator pins (16) until the pump body is firmly in position.

3. Fit new tab washers to the two pump body retaining bolts (15) and tighten to a torque setting of 41 Nm (30 lb.ft.). Bend over the tabs of the washers to secure the retaining bolts.

4. Slide the hub (14) into position on the centre shaft.

5. Check that the weir deflector arm is pointing in an anti-clockwise direction when viewed from the cover end.

NOTE: If the deflector arm was removed during disassembly, refit using Locktite 648 on the securing bolt

6. Install a rotor plate (11) and...

...then a stator plate (12), continue with alternate rotor and stator plates until all six rotor plates are sandwiched between seven stator plates. Lightly smear the surfaces of the rotor and stator plates with retarder oil during assembly.

7. Make sure that the rotor drive slots are correctly engaged in the drive hub lugs. Make sure the stator plates are correctly located on the stator pins.

8. Install the front spacing collar (13) on the centre shaft.

9. Check the tightness of the tubing nut on the pressure test point bulkhead connector.

10. Fit a new gasket (17) over the main case studs and install the end cover making sure that the stator pins locate in their respective holes in the inside face of the cover. Make sure that the pressure test point bulkhead connector protrudes through its hole in the end cover.

11. Fit the small brass washer and nut (9) on the bulkhead connector. Install the small brass plug to seal the test point.

12. Fit the 16 washers and locknuts (10) to the main case studs and progressively tighten to a torque setting of 27-34 Nm (20-25 lbs.ft.).

13. Lightly smear the front coupling flange seal surface with oil and slide the coupling flange onto the centre shaft. Rotate the centre shaft while pushing the flange into place to ensure that the garter spring in the seal is not ejected.

14. Install the rear spacer (8) on the centre shaft.

15. Lightly smear the rear coupling flange seal surface with oil and slide the coupling flange onto the centre shaft making sure that the bolt holes in the front and rear coupling flanges are in radial alignment. Rotate the retarder shaft while pushing the flange into place to ensure that the garter spring in the seal is not ejected.

16. Fit the coupling flange retaining washers and locknuts to both ends of the centre shaft...

...and tighten the locknuts to a torque setting of 544-814 Nm (400-600 lbs.ft.).

17. Carefully insert the small piston into position in the bore of the valve block top cap.

NOTE: Be very careful not to drop the piston into the main casing.

18. Fit the operating cylinder to the retarder casing using the same number of gaskets and spacers between the operating cylinder and main casing.

NOTE: The thickness of this gasket and spacer pack determines the retarder first stage operating pressure. Any change of this thickness will therefore not give the same level of performance as previously.

19. Lightly smear the sealing face of the operating cylinder with 7M7260 sealant and assemble to the retarder casing using a new gasket. Tighten the retaining screws to a torque setting of 24-27 Nm (18-29 lbs.ft.).

20. Fit the oil outlet body using a new 'O' ring seal (2) and replace the old gasket(s) with the same number of gaskets (3).

21. Place the oil outlet body as shown on the main casing and tighten the four retaining screws to a torque setting of 14-16 Nm (10-12 lbs.ft.).

Disassemble Valve Unit

1. Unscrew the four countersunk screws (1) holding the valve block to the port body casting.

2. Remove the face plate (2).

3. Lift away the valve block. Discard the gasket (3).

4. Remove the oil supply spacer (4) with 'O' rings. Discard the 'O' rings.

5. Remove the four screws securing the top plate (5) to the valve block.

6. Remove the top plate (5).

7. Withdraw the piston and spring assembly complete from the valve bore.

Inspect/Replace Worn Parts

1. Check the condition of the valve block bore for wear or scoring. If suspect replace the complete valve unit.

2. Inspect the top and bottom pistons for wear or scoring. If suspect replace the complete valve unit.

3. Inspect the base plate (1) and renew if worn. Check the condition of the pressure testing pipe (2) and the securing nut (3) for tightness.

4. Check that the ball in the reversing valve (4) is free (It should rattle if the valve block is shaken). Replace the reversing valve complete if suspect.

5. Inspect the top cap. The latest valves have a 10mm diameter through hole (5). Early top caps with 8mm diameter through holes should be modified by drilling out to 10mm diameter.

Assemble Valve Unit

New Parts Required

1. Assemble the top piston (1), inner (2) and outer (3) springs and bottom piston (4) as shown.

2. Insert the piston and spring assembly into the valve bore.

NOTE: Adjust the gap, if necessary, between the bottom piston and the outlet port to 0.4mm (0.016") by means of the capscrew and locknut on the end of the bottom piston (4).

3. Fit the top plate (5) and secure using the four retaining screws.

4. Fit new 'O' rings to the oil supply spacer (6) and insert the spacer into its position.

5. Fit a new gasket (7) and position the valve block.

6. Install the face plate (8)...

7. ...and install the complete valve unit to the port body casting using the four countersunk screws. Tighten the screws to a torque setting of 24-27 Nm (18-20 lbs.ft.)

Disassemble Pump

1. Undo the six screws (1) retaining the port body (2) to the pump body (3) and...

2. ...separate the port body and centre shaft from the pump body.

3. Withdraw the pump rotor (4) from the centre shaft.

4. Remove the pump annulus (5) from the pump body.

Inspect/Replace Worn Parts

1. Check the condition of the ball bearing (1). Replace if suspect.

2. Inspect the surface of the port plate (2) within the port body. If this is scored it can be withdrawn from the roll pin (3) and turned over.

3. Check the condition of the back face and eccentric bore of the pump body. If deeply scored or worn the assembly must be replaced.

4. Inspect the side faces and rotor tip surfaces of the pump rotor (4) and annulus (5). If deeply scored or worn the pump assembly must be replaced.

Maximum pump clearances:

Axial = 0.1mm (0.004")

Tip = 0.25mm (0.010")

Assemble Pump

New Parts Required

1. Fit new O-rings to the centre shaft (1) and insert the shaft through the port body.

NOTE: The latest units do not have O-rings fitted to the centre shaft.

2. Slide the pump rotor (2) onto the centre shaft. Make sure the port plate (3) is sitting squarely within its bore and the roll pin is in position.

NOTE: The latest units have a Woodruff key arrangement to position and secure the pump rotor onto the centre shaft.

3. Insert the pump annulus (4) into the pump body.

4. Position the port body and slide into the pump body.

5. Apply a coating of Locktite 648 and screw in the six retaining screws (5) finger tight initially then progressively tighten to a torque setting of 24-27 Nm (18-20 lbs.ft.). Check that the pump assembly rotates smoothly. Check the tightness of the two capscrews (6) holding the bellows assembly to the pump body.

Disassemble Operating Cylinder

1. Carefully separate the bellows assembly (1) complete with spacers and gaskets from the cylinder (2). Make a note of the number of gaskets used in the gasket pack. Retain the gaskets and spacers.

2. Tap the cylinder (2) on a block of wood to remove the first stage piston (3). Remove the 'O' rings (4) and discard.

3. Remove the small spring (5) from the spindle.

Assemble Operating Cylinder

New Parts Required

1. Install the small spring (5) on the new bellows assembly.

2. Fit new 'O' rings (4) to the first stage piston. Lightly smear the 'O' rings with 5P3975 rubber lubricant and insert the piston (3) into the cylinder (2).

3. Assemble the operating cylinder. Make sure the gasket pack used is to the same thickness as that originally fitted. This ensures correct retarder first stage operating pressure. See step 18 of Assemble Retarder procedure.

RETARDER GENERAL ARRANGEMENT - EARLY TYPE